This invention relates to an instrument for generating an alarm when a resting patient's heart rate or respiratory rate varies from previously established values. This device is useful in monitoring patients with fluctuating heart and respiratory rates which may be indicative of potential life threatening emergencies, such as Sudden Infant Death Syndrome (SIDS), nocturnal apnea, suffocation, and certain diseases of the heart which causes rapid or diminished cardiac rates.
Present instruments used to monitor apnea and bradycardia rely on two separate sensors that attach physically to the patient. These devices restrict the patient's movements, and are very uncomfortable especially when used on neonatal infants. In addition, the complexity of obtaining positive mechanical probes attached to the patient and the electrical connections required, make the use of these sensors cumbersome and ineffective due to the danger of separation of the probes from the patient. The complexity of these instruments also requires professional operators for best results to operate the device.
In a previous patent application, Ser. No. 129,588, I have described a device that is non-invasive and is placed on any part of a conventional bed or crib where the patient rests to monitor the heart and breathing functions. The present invention describes a single sensor which is sensitive to both the heart beat and breathing functions. An improved electronic circuit has been achieved which takes advantage of the dual sensor capabilities to detect deviations of these functions. The electronic circuit is capable of producing an alarm when a deviation from present limits occurs.